1. Technical Field
The present disclosure relates to semiconductor devices and, particularly, to a gallium nitride-based semiconductor device and a method for manufacturing the gallium nitride-based semiconductor device.
2. Description of Related Art
Gallium nitride has a relatively wide, direct band gap which permits highly energetic electronic transitions to occur. Such electronic transitions can result in gallium nitride having a number of attractive properties including the ability to efficiently emit blue light, the ability to transmit signals at high frequency, and others. Accordingly, gallium nitride is being widely used in many microelectronic applications such as transistors, field emitters, and optoelectronic devices.
At present, a mainstream method for forming a gallium nitride layer is growing the gallium nitride layer on a sapphire substrate; however, because the sapphire substrate has an inferior heat-conducting property and is very expensive, more and more silicon substrates are used for growing the gallium nitride layer. However, referring to FIG. 3, the gallium nitride has a different thermal expansion coefficient from that of the silicon substrate. This difference in thermal expansion can lead to crack of a gallium nitride layer deposited on the silicon substrate when the structure is cooled, for example, during a processing of the semiconductor structure. The cracks in the gallium nitride layer significantly affect the production yield of the semiconductor device.
What is needed is a substrate which can ameliorate the problem of the prior art.